Problem: A goblet contains $5$ red balls, $3$ green balls, and $10$ blue balls. If a ball is randomly chosen, what is the probability that it is not blue?
Solution: There are $5 + 3 + 10 = 18$ balls in the goblet. There are $10$ blue balls. That means $18 - 10 = 8$ are not blue. The probability is $ \frac{8}{18} = \dfrac{4}{9}$.